At 300 K the data below were obtained for two gaseous reactants:
Energy threshold (kJ mol⁻¹) | Fraction of molecules with energy ≥ threshold
X₂ (Eₐ = 80 kJ mol⁻¹) | 0.040
Y₂ (Eₐ = 55 kJ mol⁻¹) | 0.120
The initial concentrations are [X₂] = 0.50 M and [Y₂] = 0.30 M. Assuming the collision frequencies per unit concentration and orientation factors are identical for both gases, determine the ratio of their initial reaction rates, rate₍Y₂₎ ⁄ rate₍X₂₎.